1. Field of the Invention
The present invention relates to a chemical amplification type positive resist composition.
2. Prior Art
For fine processing of semiconductors, a lithography process using a resist composition is usually adopted, and in lithography, it is theoretically possible to increase resolution higher when exposure wavelength is shorter as represented by the Rayleigh diffraction limitation formula. As the exposure light source for lithography used for production of semiconductors, there are g ray having a wavelength of 436 nm, i ray having a wavelength of 365 nm, KrF excimer laser having a wavelength of 248 nm and ArF excimer laser having a wavelength of 193 nm, developed in this order, the wavelength becoming shorter year by year. Further, as the exposure light source of the next generation, F2 excimer laser having a wavelength of 157 nm is promising. For exposure to KrF excimer laser and ArF excimer laser, what is called chemical amplification type resists utilizing the catalytic action of an acid generated by exposure are often used due to excellent sensitivity. Further, also for exposure to F2 excimer laser, there is a high possibility of use of chemical amplification type resists due to excellent sensitivity.
However, resins used in resists for KrF excimer laser exposure and ArF excimer laser exposure do not show sufficient performance for lights of wavelengths of 170 nm or less, for example, F2 excimer laser having a wavelength of 157 nm.
An object of the present invention is to provide a resist composition which is suitable for F2 excimer laser lithography, and which show excellent in various resist properties such as sensitivity, resolution and the like, and especially excellent in durability against dry etching.
The present inventors have found that a resist composition showing improved durability against dry etching as well as excellent in properties such as sensitivity, resolution and the like can be produced by using a resin, which contains a structural unit having a specific skeleton, and a polyfunctional epoxy compound.